Despite the growing number of binary black hole coalescences confidently observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include the effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that have already been identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total source-frame mass M > 70 M _⊙) binaries covering eccentricities up to 0.3 at 15 Hz emitted gravitational-wave frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place a conservative upper limit for the merger rate density of high-mass binaries with eccentricities 0 < e ≤ 0.3 at 16.9 Gpc⁻³ yr⁻¹ at the 90% confidence level.

CHANG-ES (Continuum Halos in Nearby Galaxies—an EVLA Survey) is an ambitious project to target 35 nearby disk galaxies that are edge-on to the line of sight. The orientation permits both the disk and halo regions to be studied. The observations were initially at 1.5 GHz (L-band) and 6.0 GHz (C-band) in a variety of VLA array configurations, and in all four Stokes parameters, which allowed for spatially resolved images in total intensity plus polarization. The inclusion of polarization is unique to an edge-on galaxy survey and reveals the galaxies’ halo magnetic fields. This paper will summarize the results to date, some of which are new phenomena, never seen prior to CHANG-ES. For example, we see that ‘X-type’ fields, as well as rotation measure reversals, are common features of spiral galaxies. Further observations at 3.0 GHz (S-band) as well as future scientific opportunities will also be described.

The Local Group compact elliptical galaxy M32 hosts one of the nearest candidate supermassive black holes (SMBHs), which has a previously suggested X-ray counterpart. Based on sensitive observations taken with the Karl G. Jansky Very Large Array (VLA), we detect for the first time a compact radio source coincident with the nucleus of M32, which exhibits an integrated flux density of at 6.6 GHz. We discuss several possibilities for the nature of this source, favoring an origin of the long-sought radio emission from the central SMBH, for which we also revisit the X-ray properties based on recently acquired Chandra and XMM-Newton data. Our VLA observations also discover radio emission from three previously known optical planetary nebulae in the inner region of M32.

Superbubbles in the nuclear region of galaxies could be produced by active galactic nuclei (AGN) or nuclear starburst via different driving forces. We report analysis of the multiwavelength data of the kiloparsec-scale nuclear superbubble in NGC 3079 in order to probe the mechanisms driving the expansion of the superbubble. Based on the Chandra X-ray observations, we derive the hot-gas thermal pressure inside the bubble, which is about 1 order of magnitude higher than that of the warm ionized gas traced by optical lines. We derive a [C ii]-based star formation rate (SFR) of SFR ∼ 1.3 M _⊙ yr⁻¹ from the nuclear region using the SOFIA/FIFI-LS observation. This SFR infers a radiation pressure toward the bubble shells much lower than the thermal pressure of the gases. The Very Large Array radio image infers that magnetic pressure at the northeast cap above the superbubble is less than the thermal pressure of the hot gas enclosed in the bubble but has a clearly larger extension. The magnetic field may thus still help to reconcile the expansion of the bubble. The observed thermal energy of the hot gas enclosed in the bubble requires an energy injection rate of ≳10⁴² erg s⁻¹ within the bubble’s dynamical age, which is probably larger than the power provided by the current nuclear starburst and the parsec-scale jet. If this is true, stronger past AGN activity may provide an alternative energy source to drive the observed bubble expansion.

We report the discovery of the 10 kpc scale radio lobes in the Sombrero galaxy (NGC 4594), using data from the Continuum Halos in Nearby Galaxies—an Expanded Very Large Array Survey project. We further examine the balance between the magnetic pressure inside the lobes and the thermal pressure of the ambient hot gas. At the radii r of ∼(1–10) kpc, the magnetic pressure inside the lobes and the thermal pressure of the ambient hot gas are generally in balance. This implies that the jets could expand into the surroundings to at least r ∼ 10 kpc. The feedback from the active galactic nucleus jet responsible for the large-scale lobes may help to explain the unusually high X-ray luminosity of this massive quiescent isolated disk galaxy, although more theoretical work is needed to further examine this possibility.

The Andromeda galaxy (M31) hosts one of the nearest and most quiescent supermassive black holes, which provides a rare, but promising opportunity for studying the physics of black hole accretion at the lowest state. We have conducted a multifrequency, multi-epoch observing campaign, using the Karl G. Jansky Very Large Array (VLA) in its extended configurations in 2011–2012, to advance our knowledge of the still poorly known radio properties of M31*. For the first time, we detect M31* at 10, 15, and 20 GHz and measure its spectral index, α ≈ −0.45 ± 0.08 (S _ν ∝ ν ^α ), over the frequency range of 5–20 GHz. The relatively steep spectrum suggests that the observed radio flux is dominated by the optically thin part of a putative jet, which is located at no more than a few thousand Schwarzschild radii from the black hole. On the other hand, our sensitive radio images show little evidence for an extended component, perhaps except for several parsec-scale “plumes,” the nature of which remains unclear. Our data also reveal significant (a few tens of percent) flux variation of M31* at 6 GHz, on timescales of hours to days. Furthermore, a curious decrease of the mean flux density, by ∼50%, is found between VLA observations taken during 2002–2005 and our new observations, which might be associated with a substantial increase in the mean X-ray flux of M31* starting in 2006.